Regarding the issue of extremely low liquid level in floating roof tanks
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This post was last edited by long429l on 2017-11-22 at 13:55. SH3007-2014 Code for Design of Storage Areas in Petrochemical Storage and Transportation Systems, 4.1.9 b): The designed low liquid level for floating roof tanks or internal floating roof tanks should be 0.2 m higher than the height at which the floating roof touches the ground; CNPC Technical Guidelines for Light Oil Storage Tanks (Trial Version 2012), 7.2.3.6: The setting height for the low-low liquid level alarm in floating roof tanks is the height of the floating raft support plus 200 mm (to ensure that the ventilation holes of the floating roof are closed)； HG21502.2-1992 Steel Vertical Cylindrical Internal Floating Roof Storage Tanks Series 2.10.3 Support Height of the Internal Floating Roof: This standard specifies two support heights for the internal floating roof – one for operational purposes and another for maintenance. The operational height is 900 mm, while the maintenance height is 1800 mm. Regarding the minimum liquid level in floating roof tanks, the relevant specifications are as mentioned above; however, since no actual site conditions have been observed, previous designs have all assumed a height of 1800 mm. In accordance with the specifications, it is possible to use a height of 900 mm instead ； May I ask, in the field of storage tank design, what is the typical height at which the floating disk touches the ground when designing for a low liquid level?
Current floating platforms are generally designed at 1800mm, but they have a vent hole with a height of around 2000mm. Therefore, the low liquid level should be above the height of this vent hole. For multi-point security, around 2200 should suffice.
The float height should be determined based on the support height below the float in the storage tank